General metabolism of the retina and pigment epithelium was studied in cultured cells and in freshly dissected tissues. Glucose uptake was found to be by a facilitated diffusion mechanism. Phagocytosis was dependent on the continuous production of ATP via the TCA cycle. Glucose is the predominant energy source for cultured PE cells although glutamine can be used to maintain cells in a stable, non-dividing state and thus can probably function as an important alternative energy source in vivo.